This invention relates to a reversible rotary compressor adapted for use in refrigeration systems, and more particularly as applied to heat pump type air conditioners wherein the operation of the refrigeration system can automatically be switched from cooling operation to heating operation, or vice versa, without using a directional control valve which has been employed in conventional heat pump type air conditioners for changing the direction of flow of a refrigerant passing through a refrigerant circuit.
Conventional compressors for refrigeration systems are generally classified into reciprocation and rotary types. The reciprocating type compressor has the disadvantage that the flowing direction of refrigerant cannot be reversed. The rotary type compressor generally has a suction port only on the suction side and a discharge port only on the discharge side with respect to the pressure transition point. With the suction and discharge directions so fixed, practical use of such a compressor as a reversible compressor is not possible.
One form of a reversible rotary compressor is described in U.S. Pat. No. 2,342,174 wherein a mechanically operated reversing valve is arranged in the compressor casing. The reversing valve includes a member that is mechanically engaged by a member mounted on the motor compressor shaft to shift the valve member when direction of the shaft is reversed. U.S. Pat. Nos. 2,844,945 and 2,976,698 disclose another form of a reversible rotary compressor employing various valves and refrigeration and air conditioning system configurations, and more particularly for defrosting freezer evaporators of two-temperature systems. In U.S. Pat. No. 3,723,024, a reversible rotary compressor is disclosed wherein a movable suction mechanism is provided that is rotated through a predetermined angle so that the suction opening may be shifted to one side or the other of the pressure transition point. In still another prior art patent, U.S. Pat. No. 3,985,473, a reversible rotary compressor is disclosed wherein the single vane automatically controls the flow of fluid through the compressor to maintain it in the same direction through the compressor regardless of the direction of the compressor drive.